The present invention pertains to a sewing unit according for sewing pockets folded over in the edge area on a fabric part with a said sewing machine, a guide for moving a fabric holder from a feeding area to a sewing machine, a device for raising and lowering the fabric holder, a first bracket, which can be moved by a drive device at least between a raised position and a lowered position, a second bracket, which can be moved by a drive device at least between a raised position and a lowered position as well as between a pushed-forward position and a withdrawn position, and a control unit with memory.
Two fundamentally different processes for sewing pockets folded over in the edge area on large-large-area fabric parts have been known, which may be, e.g., shirt front parts or jeans. In one process, which is known, e.g., from German Auslegeschrift DE-AS 1 168 230 (U.S. Pat. No. 3,216,383), prefolded pockets are placed on the fabric part and are subsequently sewn on. A clamp, which receives the pocket and is displaceably arranged on a carrying frame for the fabric part, is used to accurately place the pocket on the fabric part. The prefolding of the pockets is performed here on folding presses which are equipped with replaceable folding tools adapted to the particular shape and size of the pocket. After folding over, the fold of the edge areas is fixed by pressing it under the effect of heat. Since even irregularly folded areas are now pressed flat to the extent that they will not be particularly disturbing thereafter, the folding device of folded presses may have a comparatively simple design.
In another process, known, e.g., from German Utility Model DE-GM 1 964 067 (U.S. Pat. No. 3,528,378) or DE-C1 41 13 131 (U.S. Pat. No. 5,211,320), flat pocket cuts are folded over in the edge area by means of the folding device on a sewing unit having a sewing machine and a folding device and then taken over by the program-controlled fabric holder of the sewing unit and fed to the sewing machine. Such folding devices comprise a pressure plate arranged on a first bracket and a plurality of folding slides, which are arranged on a frame likewise arranged on the first bracket and can be moved to and fro by means of compressed air cylinders between an inoperative position and a folding position. The first bracket can be moved into three different height positions, namely, an upper inoperative position, a folding position located under it, and a lower transfer position. A pocket support plate is arranged on a second bracket. The second bracket can be moved essentially into two different height positions, namely, an upper insertion and folding position corresponding to the middle position of the first bracket and a lower pressing position for the folded-over edge sections of the pocket located on the pocket support plate, which position corresponds to the lower position of the first bracket. If necessary, the pocket support plate can also be moved into a third height position, in which it floats just above the fabric part, for the accurate alignment of patterned pockets and fabric parts according to the pattern.
Since the folded-over pockets are taken over by the fabric holder without an intermediate pressing on of the edge areas in this process, the folding-over operation must be carried out particularly accurately, but this contributes to an especially accurate and clean work result being achieved. The folding devices used or integrated in sewing units are therefore comparatively more complicated and therefore more expensive that the folding devices used on folding presses.
Since the folding devices used to fold over pockets generally comprise a larger number of components adapted to the particular shape and size of the pocket, correspondingly adapted, different folding devices must be kept ready for different pocket shapes and sizes and replaced as needed. In the case of frequently changing pocket shapes and pocket sizes, this leads to a correspondingly great effort in sewing units with integrated folding device.
The basic object of the present invention is to make it possible to change the pocket shapes and pocket sizes at a low effort during the sewing on of pockets folded over in the edge area.
According to the invention, a sewing unit is provided for sewing pockets folded over in the edge area on a fabric part. The sewing unit includes a sewing machine, a fabric holder, and a guide for moving a fabric holder from a feeding area to the sewing machine. A fabric holder movement arrangement is provided with a device for raising and lowering the fabric holder, a first bracket, which can be moved by a first drive device at least between a raised position and a lowered position and a bracket, which can be moved by a second drive device at least between a raised position and a lowered position as well as between a pushed-forward position and a withdrawn position. A control unit is provided with a memory device for carrying out a programmed function of the different drive devices with integrated stop and intermediate start functions. A holder is provided formed by one of a pocket support plate associated with a folding device for the processing of pockets to be folded over and by an insertion frame in combination with a pocket pressure plate for the processing of prefolded pockets, said holder being provided at the brackets. A plurality of control programs associated with various processing variants are stored in the memory means of the control device and can be called up as needed. The processing varianets may be coordinated with the holder employed.
Due to the measure of arranging, as is known, either holding and folding means for carrying out a folding-over operation or support and holding means for, e.g., pockets prefolded on a folding press at the two movable brackets of a sewing unit or of providing such support and holding means directly at the fabric holder and of calling up the correct control program from the data memory of the control, the sewing unit can be changed over from one mode of operation to the other, i.e., from the processing of pockets to be folded over to the processing of prefolded pockets, without an appreciable effort. It is thus made possible that the expensive holding and folding means used for folding over on the sewing unit continue to be reserved for the processing of pockets generated in large numbers and/or for obtaining an especially accurate folding result, whereas in the case of frequent changeover between pockets produced in small lot sizes, the pockets are processed in the prefolded state, which will then make possible the use of the less expensive folding devices for the folding presses and of the simple support and holding means at the sewing unit.
Since pocket presses are already available in many, especially smaller sewing shops and the comparatively simple folding devices used for this purpose as well as the likewise simple support and holding means (holder) for the prefolded pockets can be manufactured without an appreciable effort in the sewing shops or workshops located close by and thus on the site, it is thus possible to respond to fashion effects in a short time by processing prefolded pockets.
Accurate mutual alignment of the pocket and the fabric part can be achieved during the processing of prefolded pockets according to a first embodiment by the insertion frame being lowered onto the fabric part with a weak force only or being held in a suspended position just above it, as a result of which the fabric part continues to be displaceable, and, furthermore, by the insertion frame either being designed as a thin-walled frame or being manufactured from a transparent material to achieve the most unhindered observability possible of the relative positions of the pocket and the fabric part.
Particularly narrow seam distances from the edge of the pocket can be obtained during the processing of prefolded pockets according to a second embodiment. This is due to the fact that the holding flap used to hold down the pocket inserted into the recess of the fabric holder does not have to hold the pocket at its edge from the outside, as in the other two processing processes and, as a consequence of this, it does not have a sewing slot corresponding to the shape and width of the seam, but it holds the pocket at a spaced location from its edge. This makes it possible to form the seam or, in the case of a double seam, the outer seam in cooperation with a holding-down foot moving up and down with the rhythm of sewing at the shortest possible distance from the free edge of the pocket.
The above-mentioned holding flap at the fabric holder can be brought into the closed or hold-down position during the sewing operation either by a floating foot arranged at the pressure bar of the sewing machine or, according to claim 6, by an actuating means, e.g., a compressed air cylinder.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.